Different WAAS altitude readings

On Sun, 27 Jun 2004 04:49:52 GMT, "Wyatt Emmerich"
wrote:

Interesting. Could you elaborate?

On what?

If you look through the NOAA site (especially the ngs pages) and also
GOOGLE the topic, you'll find lots of information on altitude standards.

The FAA site has information on TSO146 and WAAS.

I know that here in the NE, a few hundred feet discrepancy between baro
altitude and GPS altitude is not unusual with a TSO146 box.


Ron (EPM) (N5843Q, Mooney M20E) (CP, ASEL, ASES, IA)

But this was the difference between two GPS altitudes, both reporting that
they had WAAS receptivity.

"Ron Rosenfeld" wrote in message
news
On Sun, 27 Jun 2004 04:49:52 GMT, "Wyatt Emmerich"
wrote:

Interesting. Could you elaborate?

On what?

If you look through the NOAA site (especially the ngs pages) and also
GOOGLE the topic, you'll find lots of information on altitude standards.

The FAA site has information on TSO146 and WAAS.

I know that here in the NE, a few hundred feet discrepancy between baro
altitude and GPS altitude is not unusual with a TSO146 box.


Ron (EPM) (N5843Q, Mooney M20E) (CP, ASEL, ASES, IA)

On Sun, 27 Jun 2004 13:49:48 GMT, "Wyatt Emmerich"
wrote:

But this was the difference between two GPS altitudes, both reporting that
they had WAAS receptivity.

And as I posted, you were using two different non-certified units.

What makes you believe they were using the same standards and algorithm to
translate the GPS signal into an equivalent for a barometric altitude.

You can obtain further information from the sites I mentioned, and by using
Google.


Ron (EPM) (N5843Q, Mooney M20E) (CP, ASEL, ASES, IA)

Got it. Thanks for your help. I found the following on the net and it was
most useful.

http://www.esri.com/news/arcuser/0703/geoid2of3.html

"Ron Rosenfeld" wrote in message
...
On Sun, 27 Jun 2004 13:49:48 GMT, "Wyatt Emmerich"
wrote:

But this was the difference between two GPS altitudes, both reporting
that
they had WAAS receptivity.

And as I posted, you were using two different non-certified units.

What makes you believe they were using the same standards and algorithm to
translate the GPS signal into an equivalent for a barometric altitude.

You can obtain further information from the sites I mentioned, and by
using
Google.


Ron (EPM) (N5843Q, Mooney M20E) (CP, ASEL, ASES, IA)

Ron Rosenfeld wrote in message . ..
On Sun, 27 Jun 2004 04:49:52 GMT, "Wyatt Emmerich"
wrote:

Interesting. Could you elaborate?

On what?

If you look through the NOAA site (especially the ngs pages) and also
GOOGLE the topic, you'll find lots of information on altitude standards.

The FAA site has information on TSO146 and WAAS.

I know that here in the NE, a few hundred feet discrepancy between baro
altitude and GPS altitude is not unusual with a TSO146 box.


Ron (EPM) (N5843Q, Mooney M20E) (CP, ASEL, ASES, IA)

I believe there's only a couple of avionics units that were first out
of the gate to be 'partially' certified at this point (Chelton for
Capstone project and UPSAT). This may have changed as it's right on
the leading edge of happening, but my understanding was (at least as
of a few months ago) that *none* actually had been certified yet for
vertical guidance.